Sense of smell: Get a whiff of these 5 amazing facts

We may not think we rely on smell as much as our other senses, but it’s essential to our wellbeing – and basic survival.

From the smell of baking bread, to freshly ground coffee, leaking gas or even that new-car scent, smells are around us all the time – even if we don’t always consciously realise it.

However, if this primal sense does disappear – perhaps temporarily as a result of Covid-19 or permanently due to Alzheimer’s disease or head trauma – it can have a striking effect on a person’s wellbeing.

Here are five facts about smell that might surprise you.

1. Smell helps us detect potential danger

Our sense of smell is our most rapid warning system, according to new research by Sweden’s Karolinska Institutet.

It found the olfactory organ takes up about 5 per cent of the human brain, enabling us to distinguish between millions of different smells.

A large proportion of these are associated with a threat to our health and survival, such as chemicals, rotten food or smoke.

The researchers found negative smells associated with unpleasantness or unease are processed more quickly than positive smells, triggering a physical avoidance response.

Dr Alex Russell, of Central Queensland University, agrees our sense of smell is vital for our survival.

Our smell and taste work together as basically gatekeeper senses,” he says. “Their primary goal is to try and keep you from putting stuff into your body that’s going to kill you.”

2. Smell can bring back strong memories

Smell can also trigger powerful emotional reactions, Dr Russell says.

“Our memory for smell is very strong, and emotions as well, because the smell receptors are basically linked directly into the emotion and memory parts of the brain (the limbic system),” he says.

“You might be wandering down the street and smell, I don’t know, some lavender in some bushes and go, ‘Grandma!’”

3. Smell can lure us into spending more money

There’s a whole industry encouraging you to open your wallet, known as “scent marketing”.

From the popcorn you smell in the cinema, to the candles carefully placed in a property for sale, or the ambient scenting in department stores, companies are subtly tapping into your emotions.

Dr Rodrigo Suarez, of the Queensland Brain Institute, says many companies mimic certain smells by releasing non-toxic chemicals into the air.

“It’s a way of advertising, the same way as how they would sell us an image, just using smell,” Dr Rodrigo Suarez says.

4. Smell changes as we age

Dr Suarez says as babies, our sense of smell is much better developed than our visual and auditory systems.

“In all mammals, the sense of smell during early development is critical because they really need their mother to provide milk.”

Interestingly, Dr Suarez says the odours our body produces change throughout our lives, as does our sense of smell.

“So, a baby is very different to a teenager and then an adult and an elderly person – all the chemicals that they produce are different.”

5. There’s no such thing as “super smellers”

It’s a romantic notion to believe that some people are born with a talent for sniffing out any scent, but Dr Suarez says that doesn’t happen in reality.

Some people, like perfumers or winemakers, can train themselves to a high level, however they can still only recognise a maximum of five components in any one mixture, he says.

Written by Larissa Ham.